1. Field of the Invention
The present invention relates to golf balls. Specifically, the present invention relates to golf balls that include a solid core, a mid layer, and a cover.
2. Description of the Related Art
Golf players' foremost requirement for golf balls is flight performance. In particular, golf players place importance on flight performance upon a shot with a driver. Flight performance correlates with the resilience performance of a golf ball. When a golf ball having excellent resilience performance is hit, the golf ball flies at a high speed, thereby achieving a large flight distance.
An appropriate trajectory height is required in order to achieve a large flight distance. A trajectory height depends on a spin rate and a launch angle. In a golf ball that achieves a high trajectory by a high spin rate, a flight distance is insufficient. In a golf ball that achieves a high trajectory by a high launch angle, a large flight distance is obtained. Use of an outer-hard/inner-soft structure in a golf ball can achieve a low spin rate and a high launch angle.
Golf players also place importance on spin performance of golf balls. When a backspin rate is high, the run is short. It is easy for golf players to cause a golf ball, to which backspin is easily provided, to stop at a target point. When a sidespin rate is high, the golf ball tends to curve. It is easy for golf players to intentionally cause a golf ball, to which sidespin is easily provided, to curve. A golf ball to which spin is easily provided has excellent controllability. In particular, advanced golf players place importance on controllability upon a shot with a short iron.
JP2005-224515 (US2005/0181892) discloses a golf ball that includes a core, a mid layer, and a cover. In the golf ball, the difference between the hardness of the mid layer and the hardness of the cover is small. The golf ball has excellent controllability upon a shot with a short iron.
JP2006-34740 (US2006/0025238) discloses a golf ball that includes a thin cover and a large core. In the golf ball, the large core can achieve high resilience performance.
JP2006-312044 (US2006/0252579) discloses a golf ball that includes a core, a mid layer, and a cover. In the golf ball, the difference between the hardness of the mid layer and the hardness of the cover is small. The golf ball has excellent controllability upon a shot with a short iron.
In the golf ball disclosed in JP2005-224515 (US2005/0181892), the spin rate upon a shot with a driver is high. The flight performance of the golf ball upon a shot with a driver is not sufficient. In the golf ball disclosed in JP2006-312044 (US2006/0252579) as well, the flight performance upon a shot with a driver is not sufficient.
When the golf ball disclosed in JP2006-34740 (US2006/0025238) is hit by a golf player whose head speed is low, it is unlikely to obtain a high launch angle. When the golf ball is hit by a powerless golf player with a driver, the flight performance is not sufficient.
An object of the present invention is to provide a golf ball that has excellent flight performance when being hit by a powerless golf player with a driver and has excellent controllability when being hit with a short iron.